Energy-efficient water heater; leveling concrete walkway

Plumbing and heating expert Richard Trethewey and host Kevin O'Connor replace an old tank-type water heater with a new, energy-efficient "tankless" unit that is fueled by propane. Then, Richard and Kevin, along with general contractor Tom Silva and landscape contractor Roger Cook, ask, "What is it?" Roger helps a homeowner level his sagging concrete walkway using a method called "mudjacking." Later, Tom shares a viewer tip for removing dents from a piece of wood.